CLASSIFICATION OF COAGULASE-NEGATIVE STAPHYLOCOCCI IN THE DIAGNOSTIC LABORATORY

Abstract

Coagulase-negative staphylococci (198) isolated from urine, blood cultures and pus samples were classified by 2 identification schemes, and their wall teichoic acids were determined serologically. Staphylococcus epidermidis, S. saprophyticus, and S. cohnii were identified reliably using 5 criteria; acid aerobically from sucrose, trehalose and mannitol; phosphatase production; and sensitivity to novobiocin. Further species, notably S. haemolyticus and S. hominis, could be identified when hemolysis on blood agar plates was included in the criteria group. The investigation shows that a considerable number of coagulase-negative staphylococci isolated from human specimens belong to species other than S. epidermidis and S. saprophyticus. These staphylococci can cause human infections and should be identified in the diagnostic laboratory. S. epidermidis and S. saprophyticus contained the teichoic acids previously identified in these species. S. cohnii contained the same teichoic acids as S. saprophyticus. No characteristic teichoic acid was demonstrated in the other species, but several strains contained poly C(.beta.-N-acetylglucosaminylglycerol teichoic acid).